Alpine 1243D subwoofer making no sound. No ohm reading.

I have a Alpine 1243D subwoofer that was running with a Audiobahn a2301T amp for about 3 months. Yesterday I started the car and the sub was making no sound. I connected another sub to the amp and it plays fine. I removed the sub from the box and tried to read the ohms ,but it takes no reading as if the circuit is open. I tried the multimeter on another sub and it read fine.
Any suggestions to what I should test next or what might be wrong would the sub be greatly appreciated. thank you.
The sub is rated at 600rms. 4ohms + 4ohms
The amp is rated at 210rms bridged 4 ohms.
I cant see how I could have damaged this sub playing it loud.